166 COLLECTED STUDIES IN IMMUNITY. 



be applied to a method of detecting smallest amounts of 

 mercury. 



SUBSEQUENT ADDITION. In a recent communication (Muench. med. Wo- 

 chenschr. 1902, No. 17) Matthes has completely confirmed the results of our 

 experiments so far as mammalian blood-cells are concerned. The fact that 

 other species of blood, such as frog blood studied by Matthes, after hardening 

 with mercuric chloride, do not give up their haemoglobin even in fluids rich in 

 albumin does not affect our view, but only points to a high degree of hardening 

 of the frog-blood stromata which does not permit the escape of the haemoglobin 

 even in the presence of substances abstracting mercury. We did not deny 

 that the stromata could be digested by means of proteolytic ferment. Our 

 objection was directed only to regarding the escape of haemoglobin, an indi- 

 cation of a digestion, or of digesting complements. 



